1. Field of the Invention
This invention relates to a substrate processing apparatus that applies processing onto a plurality of substrates in a batch manner and a substrate conveying apparatus installed in such a substrate processing apparatus. Examples of substrates to be processed or to be conveyed include semiconductor wafers, substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magnet-optical disks, and substrates for photomasks.
2. Description of Related Art
A batch type substrate processing apparatus that applies processing onto a plurality of substrates in a batch manner has been used as a substrate processing apparatus that applies processing using a chemical solution onto substrates such as semiconductor wafers. An example of such a batch type apparatus is disclosed in Japanese Unexamined Patent Application Publication No. H11-354604 (1999). This substrate processing apparatus includes a carrier disposing unit, a horizontally transferring robot, a posture changing mechanism, a pusher, a main transfer mechanism, and a substrate processing unit.
The carrier disposing unit provides a place for a carrier to be placed. A carrier holds a plurality of substrates piled in a vertical direction each of which assumes a horizontal posture.
The horizontally transferring robot is a vertical articulated arm type conveying robot, and is formed so as to extend and contract an articulated arm and to rotate the articulated arm around a vertical axis line. Accordingly, the horizontally transferring robot directs the articulated arm toward the carrier, and transfers the substrates piled in the vertical direction each of which assumes a horizontal posture into and from the carrier. Furthermore, the horizontally transferring robot directs the articulated arm toward the posture changing mechanism, and delivers the substrates piled in the vertical direction each of which assumes a horizontal posture to and from the posture changing mechanism.
The horizontally transferring robot has a batch hand and a one-by-one hand that are detachable from the articulated arm. The batch hand is used to transfer a plurality of substrates in a batch manner, whereas the one-by-one hand is used to transfer substrates one by one. The hands are exchanged for each other by allowing the horizontally transferring robot to access a hand exchange unit. The hand exchange unit has three hand holders that hold the batch hand, the one-by-one hand used for not-yet-processed substrates, and the one-by-one hand used for processed substrates, respectively. For example, when the batch hand is detached therefrom, and, instead, the one-by-one hand is attached thereto, the horizontally transferring robot operates to store the batch hand in the batch hand holder and to attach the one-by-one hand placed in the one-by-one hand holder to the articulated arm. Therefore, it is possible to automatically exchange the hands for each other without requiring manpower.
The posture changing mechanism is used to change the posture of the substrates piled together in a batch manner from a horizontal posture to a vertical posture or vice versa.
The pusher has a holder capable of moving in upward, downward, and horizontal directions, and delivers the substrates assuming a vertical posture in a batch manner to and from the posture changing mechanism, and delivers the substrates assuming a vertical posture in a batch manner to and from the main transfer mechanism. The holder holds the substrates with a pitch which is half as large as that of the substrates held by the posture changing mechanism. For example, twenty-five substrates are delivered from the posture changing mechanism to the holder, and then the holder is moved by a slight distance in a horizontal direction along a direction in which the substrates are piled. In this state, another twenty-five substrates are delivered from the posture changing mechanism to the holder. The twenty-five substrates that have been delivered later are allowed to enter the spaces between the twenty-five substrates that have been delivered earlier, and, as a result, a batch of substrates the number of which is fifty in total are formed on the holder. The process of forming a batch by gathering groups of substrates together in this way is called “batch organization.” When the substrates are delivered from the pusher to the posture changing mechanism, twenty-five of the fifty substrates held by the holder are delivered to the posture changing mechanism, are then changed to assume a horizontal posture, and are delivered to the horizontally transferring robot. Thereafter, the remaining twenty-five substrates held by the holder are delivered to the posture changing mechanism, are then changed to assume a horizontal posture, and are expelled by the horizontally transferring robot. The fifty substrates are thus separated into two substrate groups each of which has twenty-five substrates. The process of separating a plurality of substrates forming a batch into a plurality of substrate groups in this way is called “batch disorganization.”
The main transfer mechanism has a substrate chuck that holds a plurality of substrates forming a batch in a vertical posture, and transfers the substrates forming a batch to and from the substrate processing unit by moving the substrate chuck in a horizontal direction. To wash the substrate chuck, a chuck washing unit is disposed, for example, under a position in which substrate delivery is performed between the pusher and the main transfer mechanism.
The substrate processing unit has a plurality of processing portions disposed along a direction along which the main transfer mechanism is moved. A chemical bath, a water washing bath, and a drying portion are included in the processing portions. The chemical bath is used to immerse a plurality of substrates assuming a vertical posture in a chemical stored in the bath and to apply chemical processing onto the substrates in a batch manner. The water washing bath is used to immerse a plurality of substrates assuming a vertical posture in deionized water stored in the bath and to apply water-washing (rinsing) processing onto the substrates in a batch manner. The drying portion may apply organic-solvent (e.g., isopropyl alcohol) supply processing or liquid-shaking-off processing onto the substrates in a batch manner, for example.
The substrate processing apparatus according to the prior art mentioned above has a single substrate-conveying-path system from the pusher to the main transfer mechanism. Therefore, when not-yet-processed substrates are sent to the main transfer mechanism, already-processed substrates cannot be expelled from the main transfer mechanism to the pusher, and, when already-processed substrates are expelled therefrom, not-yet-processed substrates cannot be sent thereto. Additionally, when the not-yet-processed substrates are sent to the main transfer mechanism, a batch organization operation is required on the holder of the pusher. Therefore, there is a case in which the main transfer mechanism is compelled to remain on standby for a long time until the already-processed substrates are expelled therefrom.
A possible solution may be to provide another pusher so that one pusher is used for forward-path conveyance from the posture changing mechanism to the main transfer mechanism whereas the other pusher is used for return-path conveyance from the main transfer mechanism to the posture changing mechanism. However, a structure formed according to this possible solution inevitably cause an increase in the footprint of the apparatus.